Although typically thought of as a CNS depressant, our data along with that of others show that GHB has significant sympathomimetic cardiovascular properties. The mechanisms mediating the cardiovascular responses elicited by GHB are largely unknown. This lack of knowledge is significant given the increasing recreational use of GHB and the recent interest in its therapeutic use. The proposed studies employ a variety of techniques including radio telemetry, conscious nerve recording and state-of-the-art signal analysis techniques such as coherence analysis to characterize the cardiovascular responses elicited by GHB in conscious rats. Acute studies will 1) characterize the mean arterial pressure and heart rate responses elicited by the i.v. administration of GHB 2) determine the role of GHB and GABAb receptors in mediating the cardiovascular responses elicited by GHB and, 3) assess the potential for GHB to increase sympathetic outflow by activating forebrain sympathetic pathways. Chronic studies will, for the first time, characterize the cardiovascular responses elicited by the chronic administration of GHB and assess its potential to produce cardiac toxicity.